docs: Update version badge to take version from Maven Central

Author: avast-scala-builder

README.md

@@ -1,7 +1,7 @@
 # Scala Server Toolkit
 
 [![Build Status](https://travis-ci.org/avast/scala-server-toolkit.svg?branch=master)](https://travis-ci.org/avast/scala-server-toolkit)
-![GitHub tag (latest SemVer)](https://img.shields.io/github/v/tag/avast/scala-server-toolkit?color=white&label=version&sort=semver)
+![Maven Central](https://img.shields.io/maven-central/v/com.avast/scala-server-toolkit-pureconfig_2.13)
 [![Scala Steward badge](https://img.shields.io/badge/Scala_Steward-helping-brightgreen.svg?style=flat&logo=data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAA4AAAAQCAMAAAARSr4IAAAAVFBMVEUAAACHjojlOy5NWlrKzcYRKjGFjIbp293YycuLa3pYY2LSqql4f3pCUFTgSjNodYRmcXUsPD/NTTbjRS+2jomhgnzNc223cGvZS0HaSD0XLjbaSjElhIr+AAAAAXRSTlMAQObYZgAAAHlJREFUCNdNyosOwyAIhWHAQS1Vt7a77/3fcxxdmv0xwmckutAR1nkm4ggbyEcg/wWmlGLDAA3oL50xi6fk5ffZ3E2E3QfZDCcCN2YtbEWZt+Drc6u6rlqv7Uk0LdKqqr5rk2UCRXOk0vmQKGfc94nOJyQjouF9H/wCc9gECEYfONoAAAAASUVORK5CYII=)](https://scala-steward.org)
 
 This project is a culmination of years of Scala development at Avast and tries to represent the best practices of Scala server development